Vehicle safety and efficiency are concerns for any vehicle operator. Safety is important for the operator of a vehicle, for the passengers in the vehicle, and for others that share the road with the vehicle. Safe vehicle operation also may reduce vehicle repair costs and downtime. Efficiency also is important for the vehicle operator and the vehicle owner. Efficient vehicle operation may reduce operating and maintenance costs associated with a vehicle, thereby improving profit margins for a business that operates vehicles. Components that contribute to both vehicle safety and efficiency include axle components and drive train components. Axle components include wheels, wheel hubs, pneumatic tires, suspension components, braking components, and the like. Drive train components include a vehicle engine and components that transfer power from the engine to the drive wheels of the vehicle.
Proper maintenance of the vehicle is important to safe and efficient operation of the vehicle. Proper maintenance includes proper lubricant fluid levels, proper replacement of fluids, proper tire pressures, and the like. In the case of a pneumatic tire, for example, improper air pressure in the tire can lead to an increased likelihood of a failure of the tire due to increased heating and/or increased or uneven tread wear. Improper air pressure can also increase costs associated with operating the vehicle due to reduced life of the tire, thereby increasing replacement costs and also increased rolling friction that reduces fuel economy of the vehicle and increases fuel costs.
Accordingly, an important aspect with respect to operating any vehicle is the proper maintenance of various components to ensure proper vehicle performance. In the case of an entity that operates a number of different vehicles, such as a trucking company, such maintenance is particularly important to ensure that costs associated with vehicle operation are not unnecessarily increased. However, in many cases, the volume of maintenance checks and the time required to perform such checks, coupled with shipping and delivery deadline pressures, results in such checks being performed less often than is ideal. Additionally, the value of maintenance checks to confirm proper vehicle conditions offset some of the benefits of properly maintained vehicles due to the costs associated with performing such checks. Furthermore, when a vehicle is on the road, access to a suitable maintenance facility may be limited.
Various systems have been designed and are the subject of numerous patents that accomplish the objective of tire pressure maintenance. These systems are typically called central tire inflation systems (CTIS). The most common systems in the heavy truck industry are designed for trailers. Trailer axles are typically hollow with axle ends that commonly have a through bore. The hollow axle provides an advantageous conduit to supply air pressure to the wheel end. The wheel end assembly includes a lubrication area between the axle and the wheel further defined by plugging the through bore in the axle end and covering the end of the axle with a hub cap attached to the wheel. The wheel is supported on the axle end by wheel bearings. The bearings require lubrication and the integrity of the lubrication area is essential in maintaining the operability and life of the wheel end assembly. In order to provide pressurized air to the rotating tires, the CTIS typically includes a rotary union in the same general location as the bearings and necessarily in or adjacent to the lubrication area between the stationary axle and the wheel.
Many tire inflation systems also provide an indication that air is flowing to one or more tires. Such an indication may provide notice to an operator that there is a leak in one or more tires, or perhaps a leak in the tire inflation system. In any event, the presence of such a leak is an indication that the vehicle should be serviced to correct the problem. Traditional systems commonly rely on very simplistic flow switches which use a differential pressure to close a mechanical switch. Furthermore, traditional systems require a wiring harness to be run back to the sensor from the indicator light, thus, adding to the installation costs. Many such systems only bring information to the nose of the trailer where a driver is required to notice a light in their mirror to know that a problem exists in the system, and also only warn when flow goes to any wheel but not a specific wheel in question.
Additionally, pressure regulation is provided in many tire inflation systems. Traditional pressure regulation systems generally rely on either mechanically controlled regulation or solenoid valve controlled regulation. The mechanically spring controlled regulators have poor temperature cycling repeatability, and also experience creep or rubber changes or time, which may have a detrimental influence on the output. Further, the output of such valves only opens based on a linear spring relationship. Some systems may use electronic regulators that are controlled through a complex set of solenoid poppet valves. Such systems have the advantage of allowing for non-linear output response, but generally have slow responses and wear out over time. Such systems traditionally do not have any wireless output capabilities or wireless control capabilities. Furthermore, such systems traditionally do not have flow sensors in the control loop to allow for additional nonlinear output control methods.
Tire pressure monitoring systems are available to sense, report, and optionally record the current status and pressure history of one or more tires. An example is the BatRF® system provided by Stemco LP of Longview, Tex. Various aspects of the present disclosure provide the ability to integrate a monitoring system into the maintenance system.